The present invention relates generally to the art of chemical processing and more particularly to a device for immersing printed circuit boards and/or similar items in various liquids.
During manufacture of printed circuit boards it is common practice to utilize various liquid chemical treatments and/or water rinses. Many of the liquid chemical treatments employed are for the purpose of preparing the surfaces of circuit board inner layers and/or other components for subsequent manufacturing processes and procedures. In some liquid treatments, it is desirable to apply the liquid by spray methodology while in other instances it is desirable to immerse or submerge the circuit board in the liquid for a period of time.
One particular process wherein spray methodology had been used exclusively for the application of liquid chemical solutions and water rinses is the "Method and Device for Sequential Spray Application of Chemical Solutions Used in the Manufacture of Circuit Board Inner Layers" described in U.S. patent application Ser. No. 267,044. Specifically, the method described in Application Ser. No. 267,044 involves subjecting circuit board inner layers to sequential application of four (4) chemical treatment solutions, with intermittent water rinses. The method and device of Ser. No. 267,044 is particularly useful in carrying out treatment of circuit board inner layers using the Durabond.sup..TM. preparation process (i.e. duPont de Nemours Corp., Wilmington, Del.). In accordance with the Durabond.sup..TM. process the following chemical treatment solutions are sequentially applied to circuit board inner layers:
1. Alkaline cleaner solution (Versaclean.sup..TM. 415) PA1 2. Etching solution (SureEtch.sup..TM. 600S) PA1 3. Tin solution (Durabond.sup..TM. 600 A/B) PA1 4. Post-treatment solution (Durabond.sup..TM. 600 PD)
In accordance with the method and device of Ser. No. 267,044 each of the above-listed chemical treatment solutions are spray applied. However, it has been determined that the speed and efficiency of the Durabond.sup..TM. process and the reliability of the resultant multilayer circuit boards may be substantially improved if the tin solution (Durabond.sup..TM. 600 A/B) is applied by immersion technology, rather than spraying. Thus, there exists a present need in the art for a method and device for modifying that disclosed in Patent Application Ser. No. 264,044 so as to selectively apply the tin solution (third step in the process) by immersion technology, while continuing to apply the alkaline cleaner, etching solution and post-treatment solutions (first, second and fourth steps, respectively) by spray methodology as described in U.S. patent application Ser. No. 267,044.
There also exists a need in the art for improved, independent, immersion process machine which is adaptable for use in various manufacturing processes separate and apart from the method and device of U.S. patent application Ser. No. 267,044.